Leukoplakia is characterized from an optical viewpoint by changes in the light scattering and optical absorption properties of the mucosal lining of the mouth. Cyclo-oxygenase inhibitors are being evaluated as potential therapeutic modalities for the treatment of this disease. Instrumentation is being developed to provide a quantitative assessment of the observed change in the appearance of the affected regions of a patient's mouth in response to the Cox-inhibitors. One optical approach being assessed is optical coherence tomography (OCT). This technique provides non-invasive images of the tissue layers comparable to those obtained from histology following biopsy. However, it is expensive and unwieldy requiring sophisticated instrumentation support and skilled personnel to operate. A new optical approach is being evaluated and instrumentation developed as an alternative to OCT. Light, at a number of different incident angles, is introduced into the tissue at a single point and the subsequent re-emitted light, after propagating through the tissue undergoing scattering and absorption, is measured at a series of distal points from the point of insertion. Analysis of the data for intensity and spectral distribution provides a measure of the thickness of the mucosal layer and the spectral signature of the chromophores present in the sub-mucosal layer. Appropriate comparison with OCT will be made to determine the potential of this new instrumentation as an inexpensive alternative to OCT as a clinical tool for monitoring patients with leukoplakia.